Stopping bridge collapses
Scoured awayON AUGUST 2nd a century-old bridge carrying the road from Mumbai to Goa over the Savitri river collapsed (see picture), killing at least 20 people. The probable cause was that the river, swollen by monsoon rains, had scoured away the foundations of the bridge’s piers. Such erosion-induced collapses are not peculiar to India. In 2009 the Malahide viaduct, north of Dublin, failed similarly just after a train had crossed it. This was despite its having been inspected and pronounced safe a few days earlier. In America, meanwhile, foundation-scouring is reckoned to be the leading reason for bridge failure. Half of the 500 collapses that happened there between 1989 and 2000 were caused by it.
If detected early enough, foundation-scouring is easy to fix. Dumping rubble, known as riprap, into the water around a bridge’s piers stabilises the riverbed they are sunk into. But until now such detection has involved the deployment of teams of divers, which is expensive. Hence a search for technology which can substitute for the men and women in the wetsuits.
Ken Loh of the University of California, San Diego,…Continue reading
Source: Economist